Desiccant containing packets have been employed in small diameter receivers that are juxtaposed along one of the condenser headers in an integrated type condenser-receiver. These integrated condenser-receiver structures eliminate the need for separate tubing to connect the condenser with the receiver and have become popular due to their reduced spatial requirements. For instance, in one integrated condenser-receiver disclosed in U.S. Pat. No. 5,813,249, the overall dimensions of the integral unit are from about 300 mm-400 mm in height and about 300 mm-600 mm in width.
In the integrated type condenser-receiver design reported in the ""249 patent, the axes of the receiver canister and associated header are parallel with the canister attached to and contiguous with the header. The desiccant containing package positioned in the receiver dries refrigerant liquid (and the oil and moisture entrained therein) prior to passage of the dried refrigerant to a supercooler unit that is formed integrally with the condenser.
Due to the small diameter of the receiver canister in such integrated structures, the desiccant containing package which is to be positioned therein must also comprise a small diameter substantially cylindrical pouch or packet. Typically, automotive manufacturers desire placing a fluorescent tracer dye wafer or the like in the desiccant package so that leaks in the refrigeration system can be readily determined by use of an ultraviolet light source. See for instance U.S. Pat. Nos. 5,149,453 and 5,440,910.
At present, these tracer dye wafers are available in disk shapes having a xe2x85x9cxe2x80x3 diameter and xe2x85x9cxe2x80x3 thickness. Typically, commercial felts that are used to form desiccant containing packages are on the order of about 0.060xe2x80x3-0.120xe2x80x3 in thickness. When such conventional materials are used to form a desiccant package for reception within these small diameter receivers, the internal diameter and the internal cross sectional area thereof are so small as to hinder insertion of a dye wafer therein.
One bag used in the receiver of an integrated condenser-receiver is fabricated by folding over the felt or other bag material and then sewing the one edge shut, thus forming a lopsided tube. One end of this tube is then sewn shut and the packet created by this is filled with desiccant and then the open end is sewn shut creating the bag. The sewn edge along the length of the bag protrudes out from the surface and creates a hindrance to installing the bag in a small diameter integrated receiver condenser. The construction of the bag is labor intensive and therefore expensive to fabricate.
We have found that a very thin, non-woven porous nylon material may beneficially be used to form a desiccant containing package that will fit snugly within the aforementioned small diameter receiver or other fluid flow tube or canister of an integrated type condenser-receiver. The thinness of the material, when formed into a cylindrical cross-sectioned pouch or package, will allow sufficient room within the package for insertion of a tracer dye wafer or the like therein. At the same time, the porosity of the fabric will permit adequate fluid permeability so that the refrigerant liquid can permeate the package and dry upon contact with the desiccant housed therein.
Specifically, we have found that non-woven spun bonded nylon material available under the Cerex PBN-II designation from Cerex Advanced Fabrics, Pensacola, Florida, is especially efficacious in forming these small diameter desiccant packages. This material is also sometimes referred to as being a point bonded nylon. Although others have proposed using this particular material to form a saddle-bag shaped absorbent unit of automotive accumulators (see file history for U.S. Pat. No. 6,038,881), one artisan has opined that such use is disfavored since allegedly the material is xe2x80x9cdifficult to form thermally into concave configurations, had high scrap rates and downtime, and . . . lower thermal strength.xe2x80x9d (See file history of U.S. Pat. No. 6,038,881, Incovia Declaration, paragraphs 7 and 9.)
Accordingly, it was surprising to find that this particular non-woven material could be easily and durably formed by ultrasonic sealing methods into a small diameter, generally cylindrical shape so as to house desiccant and a tracer dye wafer therein. We have found that these generally cylindrical packets are especially useful when positioned as a desiccant package in the receiver associated with the aforementioned integrated condenser-receiver.
Additionally, so as to enhance the filtering efficacy of the desiccant package, in another aspect of the invention, a solid particle filter component and an enlarged rim area of the structure are provided as a component of the pouch to minimize bypassing of the desiccant containing package by refrigerant fluid and to enhance filtering efficacy.
The present invention thus provides an adsorbent package adapted for use in a fluid flow tube of an automotive refrigerant system. The fluid flow tube may be, for example, an accumulator or receiver/drier canister or the like. The fluid flow tube or canister has a substantially cylindrical side wall and opposing first and second end walls. An inlet opening is formed within the side wall proximate the first end wall, while an outlet opening is formed within the side wall proximate the second end wall.
The adsorbent package of the present invention includes a desiccant bag having a pouch preferably formed from a tubular strip of non-woven spun bonded nylon material. A first end of the pouch is sealed in a conventional manner to form an end seam. The interior, as defined by the pouch, is then filled with an appropriate granular adsorbent material.
In one embodiment, the second end of the pouch slidably and sealingly receives a filter cap. The filter cap includes a body having a cylindrical side wall and a porous end wall which is preferably formed integrally with the side wall. The end wall includes a plurality of apertures sized so as to permit refrigerant fluid flow but to restrict desiccant from passing therethrough. The cap further includes an attachment device for securing the pouch of the desiccant bag to the body. In one embodiment, the attachment device preferably comprises an annular ring extending radially outwardly from the body of the cap and positioned along a skirt portion extending from the cap body. A resilient sealing ring is formed proximate the porous end wall and extends radially outwardly from the body. The sealing ring forms a living seal by slidably and sealingly engaging an inner surface of the cylindrical side wall of the canister.
In operation, refrigerant flows through the inlet opening of the canister and is directed through the porous end wall of the cap by the sealing ring. As may be appreciated, all fluid flow is directed through the cap by sealing engagement between the sealing ring and the cylindrical side wall of the canister. The refrigerant flows through the cap, passing through the desiccant and pouch of the desiccant bag. The desiccant removes moisture from the refrigerant while the pouch filters solid particles from the refrigerant.
The invention will be further described in conjunction with the appended drawings and following detailed description.